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https://www.readbyqxmd.com/read/28103039/single-walled-carbon-nanotubes-mimics-of-biological-ion-channels
#1
Hasti Amiri, Kenneth L Shepard, Colin Nuckolls, Raúl Hernández Sánchez
Here we report on the ion conductance through individual, small diameter single-walled carbon nanotubes. We find that they are mimics of ion channels found in natural systems. We explore the factors governing the ion selectivity and permeation through single-walled carbon nanotubes by considering an electrostatic mechanism built around a simplified version of the Gouy-Chapman theory. We find that the single-walled carbon nanotubes preferentially transported cations and that the cation permeability is size-dependent...
January 19, 2017: Nano Letters
https://www.readbyqxmd.com/read/28102386/metal-induced-supramolecular-chirality-inversion-of-small-self-assembled-molecules-in-solution
#2
Zoran Kokan, Berislav Perić, Mario Vazdar, Željko Marinić, Dražen Vikić-Topić, Ernest Meštrović, Srećko I Kirin
A non-covalent self-assembled chiral alanyl aminopyridine ligand exhibits supramolecular chirality in solution, independent of the organic solvent used. The supramolecular chirality of the assemblies is completely inverted by complexation to zinc ions. To date, such a supramolecular metal-ligand system has not been reported in the literature.
January 19, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28102374/ethane-c-h-bond-activation-on-the-fe-iv-oxo-species-in-a-zn-based-cluster-of-metal-organic-frameworks-a-density-functional-theory-study
#3
Sarawoot Impeng, Siwarut Siwaipram, Sareeya Bureekaew, Michael Probst
We first investigate the feasibility of designing a Fe-oxo complex for the activation of alkane C-H bonds by (a) incorporating an Fe ion into a Zn-based cluster derived from a metal-organic framework (MOF) and (b) creating the Fe-oxo complex via decomposition of N2O over a Fe(2+)-substituted Zn-based cluster (Fe-Zn3O(pyrazole)6). From the energy profile, it turns out that both steps should be feasible and that the resulting Fe-oxo complex is stable. In the main step, we then investigate the reactivity of this Fe-oxo cluster for the C-H bond cleavage of ethane by calculating the reaction energy profile and analyzing the electronic structure along the relevant steps...
January 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28102356/unlocking-the-potential-of-sns2-transition-metal-catalyzed-utilization-of-reversible-conversion-and-alloying-reactions
#4
Zhi Xiang Huang, Ye Wang, Bo Liu, Dezhi Kong, Jun Zhang, Tupei Chen, Hui Ying Yang
The alloying-dealloying reactions of SnS2 proceeds with the initial conversion reaction of SnS2 with lithium that produces Li2S. Unfortunately, due to the electrochemical inactivity of Li2S, the conversion reaction of SnS2 is irreversible, which significantly limit its potential applications in lithium-ion batteries. Herein, a systematic understanding of transition metal molybdenum (Mo) as a catalyst in SnS2 anode is presented. It is found that Mo catalyst is able to efficiently promote the reversible conversion of Sn to SnS2...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28102294/novel-bio-functional-magnesium-coating-on-porous-ti6al4v-orthopaedic-implants-in-vitro-and-in-vivo-study
#5
Xiaokang Li, Peng Gao, Peng Wan, Yifeng Pei, Lei Shi, Bo Fan, Chao Shen, Xin Xiao, Ke Yang, Zheng Guo
Titanium and its alloys with various porous structures are one of the most important metals used in orthopaedic implants due to favourable properties as replacement for hard tissues. However, surface modification is critical to improve the osteointegration of titanium and its alloys. In this study, a bioactive magnesium coating was successfully fabricated on porous Ti6Al4V by means of arc ion plating, which was proved with fine grain size and high film/substrate adhesion. The surface composition and morphology were characterized by X-ray diffraction and SEM equipped with energy dispersive spectroscopy...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28101806/purification-and-characterization-of-glutamate-decarboxylase-from-enterococcus-raffinosus-tccc11660
#6
Chuanyou Chang, Jun Zhang, Shenxi Ma, Lin Wang, Depei Wang, Jian Zhang, Qiang Gao
Glutamate decarboxylase (GAD) is the sole enzyme that synthesizes γ-aminobutyric acid through the irreversible decarboxylation of L-glutamate. In this study, the purification and characterization of an unreported GAD from a novel strain of Enterococcus raffinosus TCCC11660 were investigated. The native GAD from E. raffinosus TCCC11660 was purified 32.3-fold with a recovery rate of 8.3%, using ultrafiltration and ammonium sulfate precipitation, followed by ion-exchange and size-exclusion chromatography. The apparent molecular weight of purified GAD, as determined by SDS-PAGE and size-exclusion chromatography was 55 and 110 kDa, respectively, suggesting that GAD exists as a dimer of identical subunits in solution...
January 18, 2017: Journal of Industrial Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28100855/trace-elements-as-an-activator-of-antioxidant-enzymes
#7
Marta Wołonciej, Elżbieta Milewska, Wiesława Roszkowska-Jakimiec
Oxidative stress is a state of impaired balance between the formation of free radicals and antioxidant capacity of the body. It causes many defects of the body, e.g. lipid peroxidation, DNA and protein damage. In order to prevent the effects of oxidative stress, the organism has developed defence mechanisms. These mechanisms capture and inhibit the formation of free radicals and also chelate ion metals that catalyse free radical reactions. Trace elements are components of antioxidant enzymes involved in antioxidant mechanisms...
December 31, 2016: Postȩpy Higieny i Medycyny Doświadczalnej
https://www.readbyqxmd.com/read/28100693/viral-genome-packaging-terminase-cleaves-dna-using-the-canonical-ruvc-like-two-metal-catalysis-mechanism
#8
Rui-Gang Xu, Huw T Jenkins, Maria Chechik, Elena V Blagova, Anna Lopatina, Evgeny Klimuk, Leonid Minakhin, Konstantin Severinov, Sandra J Greive, Alfred A Antson
Bacteriophages and large dsDNA viruses encode sophisticated machinery to translocate their DNA into a preformed empty capsid. An essential part of this machine, the large terminase protein, processes viral DNA into constituent units utilizing its nuclease activity. Crystal structures of the large terminase nuclease from the thermophilic bacteriophage G20c show that it is most similar to the RuvC family of the RNase H-like endonucleases. Like RuvC proteins, the nuclease requires either Mn(2+), Mg(2+) or Co(2+) ions for activity, but is inactive with Zn(2+) and Ca(2+) High resolution crystal structures of complexes with different metals reveal that in the absence of DNA, only one catalytic metal ion is accommodated in the active site...
January 18, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28099893/lead-binding-capacity-of-calcium-pectates-with-different-molecular-weight
#9
Maksim Khotimchenko, Ksenia Makarova, Elena Khozhaenko, Valeri Kovalev
Nowadays, heavy metal contamination of environment is considered as a serious threat to public health because of toxicity of these pollutants and the lack of effective materials with metal-binding properties. Some biopolymers such as pectins were proposed for removal of metal ions from industrial water disposals. Chemical structure of pectins is quite variable and substantially affects their metal binding properties. In this work, relationship between molecular weight and Pb(II)-binding capacity of calcium pectates was investigated in a batch sorption system...
January 15, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28099814/geometric-and-electronic-structures-of-dibenzo-15-crown-5-complexes-with-alkali-metal-ions-studied-by-uv-photodissociation-and-uv-uv-hole-burning-spectroscopy
#10
Yoshiya Inokuchi, Motoki Kida, Takayuki Ebata
We measure UV photodissociation (UVPD) and UV-UV hole-burning (HB) spectra of dibenzo-15-crown-5 (DB15C5) complexes with alkali metal ions, M(+)•DB15C5 (M = Li, Na, K, Rb, and Cs), under cold (~10 K) conditions in the gas phase. The UV-UV HB spectra of the M(+)•DB15C5 (M = K, Rb, and Cs) complexes indicate that there is one dominant conformation for each complex except the Na(+)•DB15C5 complex, which has two conformers with a comparable abundance ratio. It was previously reported that the M(+)•(benzo-15-crown-5) (M(+)•B15C5, M = K, Rb, and Cs) complexes each have three conformers...
January 18, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28099802/stabilization-of-giant-fullerenes-c2-41-c90-d3-85-c92-c1-132-c94-c2-157-c96-and-c1-175-c98-by-encapsulation-of-a-large-la2c2-cluster-the-importance-of-cluster-cage-matching
#11
Shasha Zhao, Pei Zhao, Wenting Cai, Lipiao Bao, Muqing Chen, Yunpeng Xie, Xiang Zhao, Xing Lu
Successful isolation and unambiguous crystallographic assignment of a series of higher carbide cluster metallofullerenes present new insights into the molecular structures and cluster-cage interactions of endohedral metallofullerenes (EMFe). These new species are identified as: La2C2@C2(41)-C90, La2C2@D3(85)-C92, La2C2@C1(132)-C94, La2C2@C2(157)-C96 and La2C2@C1(175)-C98, respectively. This is the first report for these new cage structures except D3(85)-C92. Our experimental and theoretical results demonstrate that La2C92-106 are more inclined to exist stably in the carbide form La2C2@C90-104 rather than as the dimetallofullerenes La2@C92-106 which are rationalized by considering a synergistic effect of inserting a C2-unit into the cage which ensures strong metal-cage interactions by partially neutralizing the charges from the metal ions and by fulfilling the coordination requirement of the La3+ ions as much as possible, finally unraveling the mystery of the formation mechanism of giant fullerenes...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28099412/ultrafast-nonthermal-photo-magnetic-recording-in-a-transparent-medium
#12
A Stupakiewicz, K Szerenos, D Afanasiev, A Kirilyuk, A V Kimel
Discovering ways to control the magnetic state of media with the lowest possible production of heat and at the fastest possible speeds is important in the study of fundamental magnetism, with clear practical potential. In metals, it is possible to switch the magnetization between two stable states (and thus to record magnetic bits) using femtosecond circularly polarized laser pulses. However, the switching mechanisms in these materials are directly related to laser-induced heating close to the Curie temperature...
January 18, 2017: Nature
https://www.readbyqxmd.com/read/28098987/predicting-copper-speciation-in-estuarine-waters-is-dissolved-organic-carbon-a-good-proxy-for-the-presence-of-organic-ligands
#13
Holly Beverley Clare Pearson, Sean David W Comber, Charlotte Braungardt, Paul J Worsfold
A new generation of speciation-based aquatic environmental quality standards (EQS) for metals have been developed using models to predict the free metal ion concentration, the most ecologically relevant form, to set site-specific values. Some countries such as the UK have moved towards this approach by setting a new estuarine and marine water EQS for copper, based on an empirical relationship between copper toxicity to mussels (Mytilus sp.) and ambient dissolved organic carbon (DOC) concentrations. This assumes an inverse relationship between DOC and free copper ion concentration owing to complexation by predominantly organic ligands...
January 18, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28098396/the-effects-of-chronic-cobalt-and-chromium-exposure-after-metal-on-metal-hip-resurfacing-an-epigenome-wide-association-pilot-study
#14
Julia Steinberg, Karan M Shah, Alison Gartland, Eleftheria Zeggini, J Mark Wilkinson
Metal-on-metal (MOM) hip resurfacing has recently been a popular prosthesis choice for the treatment of symptomatic arthritis, but results in the release of cobalt and chromium ions into the circulation that can be associated with adverse clinical effects. The mechanism underlying these effects remains unclear. While chromosomal aneuploidy and translocations are associated with this exposure, the presence of subtle structural epigenetic modifications in patients with MOM joint-replacements remains unexplored...
January 18, 2017: Journal of Orthopaedic Research: Official Publication of the Orthopaedic Research Society
https://www.readbyqxmd.com/read/28098337/characterisation-of-the-enzymatic-properties-of-mpapr1-an-aspartic-protease-secreted-by-the-wine-yeast-metschnikowia-pulcherrima
#15
Louwrens Wiid Theron, Marina Bely, Benoit Divol
BACKGROUND: MpAPr1, encoding an acid protease from the wine yeast Metschnikowia pulcherrima IWBT Y1123, was previously isolated and shown to display potential activity against casein and grape proteins. However, its characterisation remained partial. RESULTS: MpAPr1 was cloned into the pGAPZαA vector and transformed into Komagataella pastoris X33 for heterologous expression. After verification of activity, the enzyme properties were characterised. Protease activity within the concentrated supernatant was retained over a pH range of 3...
January 18, 2017: Journal of the Science of Food and Agriculture
https://www.readbyqxmd.com/read/28098299/vacancies-in-functional-materials-for-clean-energy-storage-and-harvesting-the-perfect-imperfection
#16
Guowei Li, Graeme R Blake, Thomas T M Palstra
Vacancies exist throughout nature and determine the physical properties of materials. By manipulating the density and distribution of vacancies, it is possible to influence their physical properties such as band-gap, conductivity, magnetism, etc. This can generate exciting applications in the fields of water treatment, energy storage, and physical devices such as resistance-change memories. In this review, we focus on recent progress in vacancy engineering for the design of materials for energy harvesting applications...
January 18, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28098280/single-lithium-ion-conducting-solid-polymer-electrolytes-advances-and-perspectives
#17
REVIEW
Heng Zhang, Chunmei Li, Michal Piszcz, Estibaliz Coya, Teofilo Rojo, Lide M Rodriguez-Martinez, Michel Armand, Zhibin Zhou
Electrochemical energy storage is one of the main societal challenges to humankind in this century. The performances of classical Li-ion batteries (LIBs) with non-aqueous liquid electrolytes have made great advances in the past two decades, but the intrinsic instability of liquid electrolytes results in safety issues, and the energy density of the state-of-the-art LIBs cannot satisfy the practical requirement. Therefore, rechargeable lithium metal batteries (LMBs) have been intensively investigated considering the high theoretical capacity of lithium metal and its low negative potential...
January 18, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28098263/a-lab-on-a-chip-for-monolith-based-preconcentration-and-electrophoresis-separation-of-phosphopeptides
#18
Monica Araya-Farias, Szymon Dziomba, Benjamin Carbonnier, Mohamed Guerrouache, Ichraf Ayed, Nacera Aboud, Myriam Taverna, N Thuy Tran
A microdevice combining online preconcentration and separation of phosphopeptides was developed in a glass microchip. An ethylene glycol methacrylate phosphate (EGMP), acrylamide (AM) and bisacrylamide (BAA) based monolith was synthesized within microchannels through a photo-driven process. Morphological investigations revealed a homogeneous monolithic structure composed of uniform nodules (∼0.8 μm), with a large pore volume (0.62 cm(3) g(-1)) and sufficiently high specific surface area (34.1 m(2) g(-1))...
January 18, 2017: Analyst
https://www.readbyqxmd.com/read/28098237/controllable-synthesis-of-tio2-fe2o3-core-shell-nanotube-arrays-with-double-wall-coating-as-superb-lithium-ion-battery-anodes
#19
Yan Zhong, Yifan Ma, Qiubo Guo, Jiaqi Liu, Yadong Wang, Mei Yang, Hui Xia
Highlighted by the safe operation and stable performances, titanium oxides (TiO2) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO2@Fe2O3 core-shell nanotube arrays with hollow interior and double-wall coating. The as-prepared architecture combines both merits of the high specific capacity of Fe2O3 and structural stability of TiO2 backbone...
January 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28098160/a-zip6-zip10-heteromer-controls-ncam1-phosphorylation-and-integration-into-focal-adhesion-complexes-during-epithelial-to-mesenchymal-transition
#20
Dylan Brethour, Mohadeseh Mehrabian, Declan Williams, Xinzhu Wang, Farinaz Ghodrati, Sepehr Ehsani, Elizabeth A Rubie, James R Woodgett, Jean Sevalle, Zhengrui Xi, Ekaterina Rogaeva, Gerold Schmitt-Ulms
The prion protein (PrP) evolved from the subbranch of ZIP metal ion transporters comprising ZIPs 5, 6 and 10, raising the prospect that the study of these ZIPs may reveal insights relevant for understanding the function of PrP. Building on data which suggested PrP and ZIP6 are critical during epithelial-to-mesenchymal transition (EMT), we investigated ZIP6 in an EMT paradigm using ZIP6 knockout cells, mass spectrometry and bioinformatic methods. Reminiscent of PrP, ZIP6 levels are five-fold upregulated during EMT and the protein forms a complex with NCAM1...
January 18, 2017: Scientific Reports
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